1. Field of the Invention
The present invention relates to a CD36 mutant gene and its use, more specifically, a method for diagnosing diseases caused by lipid metabolism abnormality using the CD36 mutant gene.
2. Background Art
The development in the search technology in heart nuclear medicine in recent years has made it possible to clinically study myocardial lipid metabolism and discuss abnormalities in the myocardial lipid metabolism in heart diseases. In particular, a number of cases of abnormal fatty acid accumulation on the myocardium in hypertrophic cardiomyopathy have been reported. However, its mechanism has not been revealed.
The heart, which is a driving device for blood circulation in the body, requires a great amount of energy even in normal state, and the energy requirement further increases during exercise and under stress. The major source of energy supply in the myocardium is long chain fatty acids and 70 to 80% of myocardial energy are deemed to be derived from long chain fatty acids. Accordingly, disorders in long chain fatty acid metabolism in the myocardium are considered to result in serious consequence. In fact, it is known that cardiac diseases including sudden death are caused by disorders in the final stage of the long chain fatty acid metabolism, namely, the incorporation system of long chain fatty acids into mitochondria (carnitine shuttle), or abnormalities in enzymes which belong to .beta. oxidation system.
Various theories were suggested for the mechanism of the incorporation of long chain fatty acids into cells, but none of them were confirmed. Recently, we identified a gene which associates with the mechanism of the incorporation of myocardial long chain fatty acids and reported that the responsible product is a glycoprotein CD36 which is usually expressed in the platelet membrane (BIO Clinica, 12 (14), 86-90 (1997)).
CD36 mutant genes so far reported include C478T substitution gene in which cytosine at position 478 of the CD36 gene (exon 4) is substituted by thymine (F. K. Schattauer Verlagsgesellschaft mbH (Stuttgart), 69(5), 481-484 (1993)), 539AC deletion gene in which adenine and thymine at positions 539 and 540 of the CD36 gene (exon 5) are deleted (Blood, 83(12), 3545-3552 (1994)), and 1159A insertion gene in which adenine is inserted at position 1159 of the CD36 gene (exon 10) (Arteriosclerosis, Thrombosis, and Vascular Biology, 16(8), 1026-1032).
However, neither relationship between these CD36 mutant genes and diseases caused by lipid metabolism abnormality nor the presence of CD36 mutant genes other than the above have not been confirmed.